Railway hand brake mechanism



Aug. 3, 1954 A. F. O'CQNNOR RAILWAY HAND BRAKE MECHANISM Filed Oct. 10,1952 [I it:

Patented Aug. 3, 1954 RAILWAY HAND BRAKE MECHANISM Arthur F. OConnor,Chicago, Ill., assignor to Union Asbestos & Rubber Company, Chicago,111., a corporation of Illinois Application October 10, 1952, Serial No.314,052

2 Claims.

This invention relates to railway hand brake mechanisms and moreparticularly to the construction of the gearing as commonly employed inhand brake mechanisms to improve the performance and safety thereof.

Hand brake mechanisms as commonly used on freight cars and the likenormally include a drum carrying a chain or cable connected to the braketo engage it. A driven gear is connected to the drum to turn it and isdriven through a small driving pinion which is turned through operatingmechanism such as a hand wheel or lever. All conventional brakemechanism currently in use, whether of the vertical hand wheel type, thelever type, or the drop type, employ such constructions.

The provision of a reliable hand brake on a railway car is an importantsafety feature. The

ability of the brake to retard or stop the car contributes materially tothe safety of the operator,

the prevention of damage to the car or its contents and elimination ofinjury or damage to other personnel and property. Heretofore seriousaccidents have occurred due to cars getting out of control because offailure of the hand gear of the hand brake mechanism.

It is one of the principal objects of the present invention to eliminateor minimize the possibility of hand brake failure due to a missing geartooth.

A further object is to provide a railway hand brake mechanism includingan extremely simple and inexpensive arrangement for insuring proper andsafe operation of the hand brake even in the event a gear tooth may bemissing.

According to one feature of the invention presently existing brakemechanisms can easily be converted to embody the principles of the invention without requiring expensive rebuilding.

A still further object is to provide a railway hand brake mechanism inwhich failure of the mechanism due to a missing tooth is eliminated bythe addition of two simple and inexpensive pinions.

The above and other objects and features of the invention will be morereadily apparent when viewed in connection with the accompanyingdrawings, in which:

Figure l is a front elevation of a brake mechanism embodying theinvention with parts in section; and

Figure 2 is a central vertical section on the line 2-2 of Figure 1.

The invention is illustrated herein in connection with a vertical handwheel type of brake mechanism although it will be understod that theseveral advantages and features of the invention are equally applicableto any other conventional type of brake mechanism such as a lever typeor drop type. The vertical wheel type illustrated comprises a housingincluding a backing plate It to be secured on a railway car and a dishedcover ll fitting over and secured to the backing plate to provide anenclosed space for the gearing mechanism. The housing encloses androtatably supports a drum shown as a relatively enlarged shaft orspindle l2 journaled at its opposite ends in the backing plate and thecover and rigidly carrying a main driven gear I 3. A tension device suchas a chain [4 for operating the brake extends through the open bottom ofthe housing for connection to the brake rigging and is anchored to thegear by means of a U-bolt l5. As the gear is turned the chain will bewrapped around the spindle l2 to apply the brake.

The driven gear and drum are turned by means of a relatively smalldriving pinion I6 which meshes with the driven gear [3 and which may beturned by any desired type of operating means such as the hand wheelpartially shown at IT. The mechanism illustrated in the presentapplication is similar to that more particularly described and claimedin my copending application Serial No. 212,306, filed February 23, 1951,al-

though it will be understood that this mechanism is selected as typicalof brake mechanisms of the type heretofore known to which the presentinvention may be applied.

In the construction shown, the hand wheel I1 is connected to a shaft l8which is journaled in the backing plate It and the cover H for freerotation. The pinion It is freely rotatable on the shaft and isconnected through pins I9 to a pressure plate 2| which is threaded on athreaded portion 22 of the shaft. The pins !9 connect the pressure plateand driving pinion against relative rotation in all relative axialpositions thereof, while permitting free axial movement therebetween.

A ratchet wheel 23 is mounted between the pinion 16 and the pressureplate 2! and is held against rotation in one direction by a pivoted pawl24.

When the hand wheel is turned clockwise as seen in Figure 1 the pawl 24will overrun the ratchet wheel and the threads 22 will cause thepressure plate 2| to move toward the pinion It so that the pinion willbe turned clockwise with the hand wheel. When the hand wheel is releasedthat as soon as the hand wheel is released the ratchet will again befrictionally gripped between the pinion and the pressure plate toeliminate free spinning of the hand wheel with the possible undesiredloss of chain tension and damage to the operator.

With a construction as so far described the mechanism will functionproperly under all conditions except when a tooth is missing from thedriven gear or the pinion. If a tooth is missing, a dead spot in theoperation of the brake will result to prevent proper application of thebrake and. possibly to release the brake for free turning to itsdisengaged position.

To eliminate this possibility, according to the present invention asecond drive pinion 25 is provided freely journaled on a stub shaft 26carried by the backing plate H] or which may extend between the backingplate and the cover so that the pinion 25 meshes with the gear 13 but isspaced from the driving pinion l6. pinion 21 journaled on a stub shaft28 carried by the backing plate l meshes with the two driving pinions l6and 25 but is spaced from and out of mesh with the driven gear. Due tothe idler pinion the two driving pinions will necessarily turn in thesame direction at the same peripheral speed so that under normalconditions the driven gear will be turned by both of the drivingpinions.

With this construction, it will be seen that if there should be amissing tooth in the driven gear it cannot register with both of thedriving pinions'at the same time so that the gear and the drum willalways be driven through at least one of the driving pinions. In theevent a tooth is missing from the driving pinion it cannotsimultaneously register with both the driven gear and the idler pinionso that the driven gear will either be driven directly from the drivingpinion or indirectly through the idler and second driving pinion at alltimes.

A further advantage of the present invention is that existing brakemechanisms can easily be modified to embody the safety features of theinvention without requiring complete rebuilding a of the mechanisms. Forexample a conventional vertical brake would include all of the elementsshown except the idler pinion 21 and second drive pinion 25. The shafts26 and 28 can easily be mounted in the existing housing of aconventional brake mechanism and the pinions can be mounted thereonwithout requiring any substantial change in the existing mechanism.

Practically all of the present geared hand brakes are designed with thesmallest pitchdiameter driving pinion consistent with needed strengthand the largest pitch-diameter driven gear consistent with spacelimitations in the brake housing, in order to obtain the maximum powerdevelopment. Numerous tests havedeveloped that there is direct relationbetween the An idler gear ratio and the ability of geared hand brakes toremain operative, with a tooth missing; most of the present hand brakesbeing inoperative if a tooth is missing. If a larger itch-diameterdriving pinion is used in the present brakes, it requires thatpractically every component part of the brake mechanism and the housingbe redesigned, as the attendant change in gear ratio will otherwiseresult in power development below the mandatory figure set up by theAssociation of American Railroads rigid specifications for acceptablehand brakes. Such redesigning of the component parts of a hand brakeinvolves new pattern equipment, dies, jigs and fixtures. In the case ofa hand brake using a pressed steel housing,-it might require newstamping dies, which are very expensive. To obtain new patterns, diesand fixtures would require a large expenditure in money and time, aswell as the re-testing of the brake, in order to obtain certification bythe Association of American Railroads, before the revised device couldbe used by the railroads. Inasmuch as the present invention requiresonly the addition of two small pinions to present geared brakestructures, at a nominal cost, the exceptional utility of the inventionin the conversion or rebuilding of existing brakes to provide the safetyand reliability desired will be apparent.

While one embodiment of the invention has been shown and describedherein, it will be understood that this is illustrative only and not tobe taken as a definition of the scope of the invention, reference beinghad for this purpose to the appended claims.

What is claimed is:

l. A railway hand brake mechanism comprising a relatively large drivengear, means connected to the driven gear to connect it to a brake, arelatively small driving pinion meshing with the driven gear, operatingmeans connected to the driving pinion to turn it, an idler pinion meshng with the driving pinion and spaced from the driven gear, and a seconddriving pinion meshing with the idler pinion and with the driven gear ata point circumferentially spaced from the first named driving pinion.

2. A railway hand brake mechanism comprising a relatively large drivengear, means connected to the driven gear to connect it to a brake, adriving pinion meshing with the driven gear, ratchet means connected tothe driving pinion normally to prevent rotation thereof in onedirection, operating means connected to the driving pinion and theratchet means to control the ratchet means to permit rotation of thedriving pinion in said one direction and to turn the driving pinion inthe other direction, a second driving pinion meshing with the drivengear and spaced circumferentially from the first named driving pinion,and an idler pinion meshing with both of the driving pinions and spacedfrom the driven gear.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,926,175 Richards Sept. 12, 1933 2,508,186 Newell May 16,1950 2,586,969 Marquardt et al. Feb. 26, 1952

